A wind turbine generator is a device that generates electricity by rotating a rotor head provided with wind-turbine blades with received wind force, and increasing the rotational speed thereof with a gearbox to drive a generator. For this reason, sliding parts requiring lubrication, for example, the gearbox, bearings, and the like, exist in the wind turbine generator, and the generator is provided with a lubricating system for supplying lubricating oil to the sliding parts from a lubricating-oil tank using a lubricating-oil pump.
In a hydraulic circuit of a hydraulic machine, a structure that easily and reliably ensures warming up operation when starting an engine and heat balance during operation has been proposed. This conventional technology has been constructed so as to provide a cooling flow path and a non-cooling flow path, differing in the presence of an oil cooler, and to be able to select and change flow paths for return oil returning to a lubricating-oil tank with a direction switching valve (for example, see Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2005-155698